Dynamic Load Balancing for EV Chargers

A home EV charger can be one of the largest electrical loads in a property.

At the same time, the home may also be running:

a heat pump
an oven
an induction hob
an immersion heater
a home battery
other household appliances

If everything demands maximum power at the same time, the total load can rise quickly.

One solution is to permanently restrict the EV charger to a lower power.

A better solution in many homes is to let the charger adapt.

Dynamic load balancing lets the EV use as much of the home’s configured electrical headroom as is currently available — and automatically reduces charging when the house needs that capacity elsewhere.

The charger can therefore:

charge faster when the home is quiet
reduce charging when household demand rises
pause if available headroom becomes too low
increase charging again when capacity returns

The objective is not to give the EV maximum power every minute.

It is to use the home’s available electrical capacity intelligently.

What Is Dynamic EV Load Balancing?

Example

The home has a configured electrical limit of 18 kW and is currently using 8 kW. That leaves 10 kW of headroom.

If the EV charger can use a maximum of 7 kW, it can charge at full power.

Later, household demand rises to 15 kW. Now only 3 kW of headroom remains, so the EV charger can reduce its charging power accordingly.

When household demand falls again, EV charging can increase.

Dynamic EV load balancing continuously adjusts EV charging power according to the electrical capacity currently available at the property.

Dynamic load balancing continuously asks one question: how much electrical headroom is available right now?

What Does “Load Balancing” Actually Mean?

The term load balancing can describe several different control jobs.

It may refer to:

one EV charger adapting to whole-home electrical demand
several EV chargers sharing a fixed charging allowance
distributing electrical load across three phases
managing several flexible loads around the whole home

For this guide, dynamic EV load balancing means:

Continuously adjusting EV charging power according to the electrical capacity currently available at the property.

This distinction matters when comparing chargers.

The important question is not whether a charger has “load balancing”. It is what electrical demand it is measuring and what it is actually controlling.

What Is Electrical Headroom?

Electrical headroom is the amount of additional power the property can use before reaching its configured electrical limit.

A simple way to think about it is:

Electrical headroom = configured site limit − current electrical demand

For example, a configured site limit of 18 kW with current demand of 10 kW gives available headroom of 8 kW.

If the EV charger wants 7 kW, there is enough headroom for full charging power.

If household demand rises to 14 kW, headroom falls to 4 kW. The EV charger can then reduce.

The charger uses the electrical capacity the house can spare, rather than assuming maximum charging power is always available.

Fixed Charger Limit vs Dynamic Load Balancing

Without dynamic load balancing, an installer may need to permanently restrict EV charging power.

For example, a maximum charger capability of 7 kW with a permanent configured limit of 3.6 kW.

That protects the electrical supply. But it also means the charger remains limited to 3.6 kW even when the rest of the house is using almost nothing.

Dynamic load balancing behaves differently.

The charger might operate at 7 kW for much of the night, then reduce temporarily when cooking starts, heat-pump demand rises, immersion heating operates or battery charging increases.

Once those loads disappear, the EV can increase again.

A fixed limit protects capacity by permanently giving some of it away. Dynamic load balancing gives that capacity back to the EV whenever the house is not using it.

The Site Limit Is Not Simply the Main Fuse Rating

It is tempting to think that load balancing simply reads the main fuse rating and tries to keep the house just below it.

That is too simplistic.

The configured electrical limit may need to consider:

the service capacity
DNO information
consumer-unit design
submain capacity
other electrical equipment
installer settings
electrical design margins

A property with a 100 A service fuse should not automatically be designed to sit continuously at 99 A.

The site limit is a design value used by the control system, not simply the number printed on the main fuse.

Load Balancing Is Not Only About the Main Fuse

The relevant electrical limit may not always be the grid connection itself.

A charger may need to respect the capacity of:

the main supply
a consumer unit
a submain
an outbuilding supply
a charger group
another part of the installation

For example, a detached garage may have its own submain with less capacity than the property’s main electricity supply.

The EV charger may therefore need to balance against that smaller limit.

The charger may be balancing against the whole grid connection, or against a smaller electrical limit elsewhere in the installation.

Staying Below the Grid Limit Does Not Guarantee Everything Is Within Limit

Important

Load balancing is useful. But it does not replace correct electrical design.

Cables, switchgear, consumer units, submains and protective equipment still need to be correctly designed for the loads they carry.

This becomes particularly important where the home also has solar PV, battery storage, multiple consumer units or bidirectional electrical flows.

Staying within the grid connection limit does not automatically prove every cable, consumer unit or part of the installation is within its own limit.

Load balancing manages demand. It does not replace correct electrical design.

Single Phase vs Three Phase Explained

How Does the Charger Know What the House Is Using?

The charger needs some way of measuring electrical demand.

Depending on the system, this might use a CT clamp, a dedicated energy meter or compatible integrated metering.

The exact hardware varies.

The important point is that the charger needs reliable information about the electrical demand at the point it is trying to protect.

To protect the whole connection, the charger needs a reliable measurement of what the whole connection is doing.

What Is a CT Clamp?

A CT, or current transformer, is commonly used to measure electrical current flowing through a conductor.

It can provide the charger or energy-management system with information about current import, changing household demand and available electrical headroom.

The charger can then adjust EV power in response.

The homeowner does not normally interact directly with the CT. It forms part of the electrical control system.

CT Clamp or Meter Position Matters

Measuring electrical demand is only useful if the measurement is taken in the right place.

A poorly positioned sensor might fail to see another consumer unit, an outbuilding, battery charging, solar generation or another significant load.

That can give the control system an incomplete picture of the property.

A load-balancing system is only as good as the electrical demand it can actually see.

This becomes particularly important as the electrical system becomes more complex.

Measure What Is Actually Happening at the Grid Connection

Dynamic load balancing should normally respond to real electrical conditions rather than theoretical appliance ratings.

Imagine household loads of 4 kW, solar generation of 3 kW and grid import of 1 kW.

Simply adding appliance loads together would suggest the house is using 4 kW from the grid. It is not. Solar is already supplying most of that demand.

Dynamic load balancing should respond to the power actually crossing the grid connection, not simply add up appliance ratings.

Solar PV Can Create EV Charging Headroom

Imagine an EV charger at 7 kW, other household loads of 5 kW and solar generation of 4 kW.

Total electrical demand inside the home is 12 kW. But solar is supplying 4 kW. Grid import is therefore approximately 8 kW.

The 7 kW charger has not increased grid import by the full 7 kW.

A 7 kW EV charge does not necessarily increase grid import by 7 kW when solar or battery power is supplying part of it.

This is why measuring the actual grid boundary is so useful.

Solar Headroom Can Disappear Quickly

Now imagine the same property with solar generation of 4 kW.

A cloud passes over. Solar falls to 1 kW.

The house has suddenly lost 3 kW of locally generated power.

Unless another load changes, grid import rises by the same amount.

Dynamic load balancing can respond by reducing EV charging if necessary.

Solar can create charging headroom, but that headroom can disappear as quickly as the weather changes.

Home Batteries Can Create or Consume Headroom

Battery Discharging: The battery supplies part of the household demand. Grid import falls. More headroom may become available.
Battery Charging: The battery becomes another electrical load. Grid import rises. Available headroom falls.

A battery changes grid demand in both directions.

A battery can create EV charging headroom while discharging and consume that headroom while charging.

This interaction becomes especially important during cheap tariff periods.

Smart Charging and Dynamic Load Balancing Are Different

Smart Charging: May respond to electricity tariffs, scheduled charging periods, app settings and remote signals. It is mainly deciding when charging should happen.
Dynamic Load Balancing: Responds to actual household demand and available electrical headroom. It is mainly deciding how much power the EV can use right now.

These terms are often confused.

Smart charging decides when the EV should charge. Dynamic load balancing decides how much power the property can spare while it is charging.

A charger can support both. But one does not automatically mean the other.

A Smart Charging Schedule Can Still Create a Bad Electrical Peak

Example

A cheap electricity period begins at midnight. Several smart devices respond at once.

EV charging 7 kW, battery charging 5 kW, heat pump 3 kW, normal household demand 2 kW. Total: 17 kW.

Then the immersion heater starts at 3 kW. Potential total demand: 20 kW.

Every device may be behaving correctly according to its own schedule. But collectively, they have created a large electrical peak.

A charging schedule can choose the cheapest time and still choose the busiest electrical time for the home.

Dynamic load balancing allows the EV charger to react to that real electrical demand.

Why EV Charging Is Particularly Suitable for Load Balancing

EV charging is unusually flexible.

The car may be plugged in for 8 hours, 10 hours or 12 hours. But it might only need a few hours of full-power charging.

That means the charger can often reduce power temporarily without affecting the driver’s next journey.

The EV does not need maximum power every minute. It needs enough energy before departure.

This is one of the main reasons EV charging is so suitable for dynamic control.

Reduced Charging Power Does Not Automatically Mean the Car Will Be Late

Imagine the EV needs 20 kWh and has 8 hours before departure.

Ignoring charging losses, the average power requirement is 20 ÷ 8 = 2.5 kW.

The charger may still spend parts of the night at 7 kW, 5 kW or 3 kW and comfortably deliver the required energy.

The important question is not whether charging was reduced. It is whether enough kWh can still be delivered before departure.

Basic Load Balancing vs Smarter Charging

Basic dynamic load balancing asks how much charging power is available right now?

That protects the electrical connection.

A more advanced charging system may also consider how many kWh are still needed, departure time, remaining charging window and tariff period.

That allows it to ask a second question: if I reduce the charger now, will the car still be ready later?

Basic load balancing protects the connection now. Smarter charging also checks whether the car is still on track for later.

Energy Priority Explained

EV Charging Has a Practical Minimum Power

Single Phase: 230 V × 6 A ≈ 1.4 kW
Three Phase: approximately 4.2 kW total

AC EV charging cannot always be reduced smoothly all the way towards zero.

There is normally a practical minimum charging current. A useful typical reference is around 6 A per phase.

These are useful illustrative figures rather than a guarantee of how every vehicle or charger behaves. Different cars and charging equipment can behave differently.

The important principle is:

EV charging cannot always be reduced smoothly towards zero. Below a certain point, pausing may be more practical than further throttling.

Sometimes Pausing Is Better Than Throttling

Imagine the home only has 0.8 kW of spare electrical headroom.

The EV may not be capable of using such a small charging input.

The charger may therefore need to pause, wait for household demand to fall and resume when enough headroom returns.

When available headroom falls below useful charging power, pausing can be better than trying to divide power that the vehicle cannot use.

Dynamic Load Balancing Has to Respond to Changing Demand

Household electrical demand can change quickly.

Examples include an electric shower starting, an induction hob switching on, an immersion heater operating, heat-pump auxiliary heating and a battery beginning to charge.

The charger needs to respond appropriately to those changes.

Dynamic load balancing has to respond to changing household demand quickly enough for the configured electrical limit to remain meaningful.

The exact control response depends on the charger and system design.

What Happens if the Load Measurement Fails?

Important

A dynamic load-balancing system depends on its measurement. So an important question is: what happens if that measurement disappears?

Examples might include CT failure, energy-meter communication loss or a local communication fault.

Different charger systems handle this differently. Possible responses can include pausing charging, reducing to a defined fallback current, or entering another safe operating mode.

A load-balancing system needs a safe answer for what happens when it can no longer measure the load.

This is an important question to ask before choosing a charger.

Local Control and Cloud Control Are Different

Some EV charging functions may depend heavily on internet or cloud services.

Examples include tariff optimisation, remote scheduling, app controls and journey planning.

Real-time electrical headroom control is a different job.

Cloud intelligence can optimise charging. Electrical headroom protection needs a robust answer even when the internet is unavailable.

The exact architecture varies by charger. The important question is whether the charger has a sensible fallback if communications are lost.

Dynamic Load Balancing Can Increase Average Charging Power

Imagine a property where an installer would otherwise permanently restrict the EV charger to 3.6 kW.

Over an 8-hour period, that gives a simplified gross charging capacity of 3.6 × 8 = 28.8 kWh.

With dynamic load balancing, the same charger might spend much of the night at 7 kW and only reduce during busy periods.

The average charging power could therefore be much higher while the property’s configured maximum electrical limit remains unchanged.

Dynamic load balancing can increase the average charging power available to the EV without increasing the property’s maximum grid limit.

Dynamic Load Balancing Can Sometimes Avoid or Defer a Supply Upgrade

Imagine a home where EV charging only becomes a problem when cooking, an electric shower and an immersion heater operate at the same time.

Those are temporary overlaps.

Instead of increasing the grid connection purely to allow the EV to stay at full power during those short periods, the charger may simply reduce temporarily.

Where the problem is overlapping flexible demand, load balancing can sometimes remove the need to reserve more grid capacity just for the EV.

This does not mean every property can avoid a supply upgrade. The installation still needs to be properly assessed.

Load Balancing Cannot Solve an Energy-Throughput Shortage

Example

The EV needs 50 kWh. The available charging window is 5 hours.

The simplified average power requirement is 50 ÷ 5 = 10 kW before charging losses.

A 7 kW charger cannot deliver 50 kWh within five hours. Dynamic load balancing cannot change that.

A Power-Overlap Problem: Loads only collide occasionally. Dynamic load balancing may solve it.
An Energy-Throughput Shortage: There is not enough charging power multiplied by available time. More time or more charging capacity may genuinely be required.

Load balancing can solve an overlap problem. It cannot create charging energy that the available power and time cannot deliver.

Single-Phase Dynamic Load Balancing

On a single-phase property, load balancing is conceptually straightforward.

The charger needs to understand the available capacity on that one supply phase.

If household demand rises, the EV can reduce. When demand falls, the charger can increase.

The precise electrical design still depends on the property.

Three-Phase Dynamic Load Balancing

Three-phase properties are more complicated.

There may be different electrical demand on L1, L2 and L3.

For example, L1 spare capacity 10 A, L2 spare capacity 30 A, L3 spare capacity 25 A.

Total spare capacity across the property may look substantial. But one phase is much more constrained than the others.

On three phase, the charger may need to respect three electrical headroom limits rather than one.

Single Phase vs Three Phase EV Charging

A Single-Phase Charger on a Three-Phase Property Still Uses One Phase

Imagine a three-phase house has a 7 kW single-phase EV charger connected to L1.

Its charging demand sits on L1.

Spare capacity on L2 and L3 cannot simply be treated as though it were directly available to that charger.

A single-phase EV charger cannot use spare capacity sitting on the other phases as though it were one shared pool.

This is why phase allocation matters.

Genuine Three-Phase EV Charging Has Different Constraints

An 11 kW or 22 kW three-phase charging arrangement draws power from all three phases.

But the available charging rate may still be affected by the most heavily loaded phase.

On a three-phase charging system, the most constrained phase can influence the charging power available across the session.

The exact behaviour depends on the charger, vehicle and electrical design.

Multiple EV Chargers Need Two Layers of Control

How Much Power Can EV Charging Use?: This is the total EV charging allowance available within the site's electrical limit.
How Should That Power Be Shared?: The available EV allowance then needs dividing between EV 1 and EV 2.

If a home has two EV chargers, load balancing becomes more interesting.

With two chargers, the system has two decisions: how much power EV charging can use, and how that power should be shared between the cars.

Charging Two EVs at Home

Equal Sharing Is Not Always the Best Sharing

Suppose EV 1 leaves at 06:00 and EV 2 leaves at 09:00.

Equal power sharing may not be the best solution. EV 1 may deserve more charging power first.

Similarly, one car may need 25 kWh while the other only needs 5 kWh.

The best power split between two EVs depends on energy requirement and departure time, not simply equal percentages.

This is where charging starts to become an energy-priority problem rather than just a load-balancing problem.

Solar Surplus Charging and Dynamic Load Balancing Are Different

Dynamic Load Balancing: Primary objective: keep electrical demand inside the configured limit.
Solar Surplus Charging: Primary objective: use surplus solar and minimise unnecessary grid import.

These two functions can use similar measurements. But they have different objectives.

Load balancing protects the electrical boundary. Solar charging tries to minimise grid import.

A charger can potentially support both. But they should not be confused.

Solar Charging and Load Balancing Can Work Together

Imagine solar generation rises during the afternoon. More surplus becomes available. The EV charger may increase.

A cloud arrives. Solar output falls. The EV charger may reduce.

Later, household demand rises. The charger may reduce again to protect site headroom.

The same charger is now responding to available solar, grid import and household demand, but each control goal is slightly different.

Battery Peak Shaving Can Preserve EV Charging Power

Imagine the EV charger is running at 7 kW and household demand rises.

Instead of immediately reducing the EV, a home battery could potentially discharge and reduce grid import.

Technically, that creates more grid headroom.

But that does not automatically mean it is the best decision. The stored battery energy may be more valuable later. Or the grid tariff may already be cheap.

Creating headroom with a battery is technically possible, but it is not automatically the best energy decision.

EV Load Balancing and Whole-Home Load Management Are Different

A charger-level load-balancing system primarily asks how much should EV charging reduce?

A whole-home load-management system can ask a broader question: which flexible load should reduce?

Possible choices include EV charging, battery charging, immersion heating and other flexible loads.

EV load balancing knows how much the charger should move. It does not necessarily know whether another flexible load should move instead.

Load Management Explained

Energy Priority Is the Next Layer

Imagine an EV departure at 06:00, optional battery charging, and a site electrical limit nearly reached.

Basic EV load balancing may reduce the EV.

But a smarter whole-home strategy may decide to reduce battery charging from 5 kW to 1 kW while EV charging remains at 7 kW, because the EV has the more urgent deadline.

Charger-level balancing protects the site. Energy priority decides which flexible load should give way.

Energy Priority Explained

Several Smart Devices Can Fight Each Other

Consider: the EV charger reduces power because grid import is high. The battery notices spare capacity and starts charging harder. The EV then sees more available capacity and increases again.

Or: the battery starts peak shaving. The EV sees extra headroom and increases charging. The battery then has to discharge even harder.

Several independently smart devices can accidentally chase the same electrical headroom.

This is why whole-home control architecture matters.

A Home Needs One Clear Control Authority

As homes become more complex, several devices may be capable of controlling electrical demand.

These can include the EV charger, battery energy-management system, HEMS and a dedicated site controller.

If several independent systems are all trying to control the same electrical boundary, their objectives can conflict.

A home needs one clear authority for deciding what happens when several smart devices compete for the same electrical capacity.

Home Energy Management Systems Explained

EV Load Balancing Is Not the Same as a Formal DNO Limit

Dynamic EV load balancing is usually a property-level demand-control strategy.

It should not automatically be confused with formal DNO import-limitation arrangements, generation connection requirements or export limitation.

Those are separate network-connection issues.

EV load balancing is a property-level demand-control strategy. It should not be confused with formal DNO import or export limitation.

DNO Import & Export Limits

Worked Example: The EV Gives Capacity Back to the House

Example

Configured site limit 18 kW. Current loads: house 3 kW, heat pump 2 kW, EV charger 7 kW. Total 12 kW. Available headroom 6 kW.

Now cooking begins: +5 kW. Total 17 kW. The EV can remain at 7 kW because the property is still below the configured limit.

Then an immersion heater starts: +3 kW. Unmanaged demand would now be 20 kW — above the 18 kW limit.

The EV charger reduces: 7 kW → 5 kW. Managed total: 18 kW.

Later the cooking load ends. Demand falls. The charger increases: 5 kW → 7 kW.

The EV receives maximum useful power when capacity exists and gives some of it back when the house needs it.

That is dynamic load balancing in its simplest form.

Worked Example: Solar Creates and Removes Headroom

Example

EV 7 kW, house 5 kW, solar 4 kW. Grid import approximately 8 kW.

Then cloud cover reduces solar generation to 1 kW. Grid import increases to approximately 11 kW.

No one has switched on another appliance. The grid demand changed simply because local generation fell.

If another large household load now starts, the EV charger may need to reduce.

Dynamic load balancing follows the electrical boundary as generation and demand change.

Worked Example: EV vs Battery Charging

Example

EV charging 7 kW, battery charging 5 kW, other household demand 5 kW. Total 17 kW.

The hob starts: +4 kW. Potential total 21 kW. Assume the configured site limit is 18 kW.

EV-only load balancing — the EV could reduce 7 kW → 4 kW. Total returns to 18 kW.

Whole-home priority control — but suppose the EV needs to leave soon. A whole-home controller could instead reduce battery charging 5 kW → 2 kW, and the EV remains at 7 kW. Total again returns to 18 kW.

Both strategies protect the site. But they make different energy decisions.

Charger-level balancing protects the site. Whole-home control can choose which flexible load should give way.

Do I Need Dynamic Load Balancing?

Understand the Electrical Supply
What is the relevant configured electrical limit?
Check the EV Charger Power
Is the proposed charger 3.6 kW, 7 kW, 11 kW, 22 kW or another rating?
Identify Other Large Loads
Examples: heat pump, induction hob, electric shower, immersion, battery charging.
Check Whether Those Loads Overlap
Does the EV charge while those loads are commonly active?
Decide Whether the Problem Is Occasional or Sustained
If overlap only happens occasionally, dynamic load balancing may be especially useful.
Check the EV's Energy Requirement
If charging power is temporarily reduced, can the car still receive enough kWh before departure?
Check the Measurement Point
Can the charger actually see the relevant whole-site demand?
Consider Solar and Battery Flows
Do local generation or storage change grid import significantly?
Check Single Phase or Three Phase
Three-phase control may need to understand each phase separately.
Consider Multiple Chargers
Does the system need to share EV power between more than one vehicle?
Check Failure Behaviour
What happens if the CT signal disappears, the energy meter stops communicating, or the internet connection fails?
Decide Whether Charger-Level Control Is Enough
If the home also has a battery, heat pump, hot-water storage or several smart loads, whole-home load management may eventually be more appropriate.

What Should You Ask Before Buying a Charger?

Do not stop at does it have load balancing?

Ask:

What does the load-balancing system measure?
Does it use a CT clamp or dedicated energy meter?
Where is that measurement taken?
Does it see the entire property?
Does it account for solar generation?
Does it account for battery charging and discharging?
Can the site limit be configured?
How low can it reduce EV charging?
Can it pause and resume automatically?
What happens if available headroom falls below minimum charging power?
What happens if the CT or meter fails?
Does load balancing operate locally?
Does it require an internet connection?
Can it control multiple chargers?
Does it support three-phase measurement?
Does it offer solar surplus charging as a separate function?
Can it integrate with a battery or HEMS?
Does it support phase switching where relevant?

“Does it have load balancing?” is not enough. Ask what it measures, what it controls and what happens when communication fails.

Common Dynamic EV Load Balancing Questions

What is dynamic EV load balancing?

It is a system that adjusts EV charging power according to the electrical capacity currently available at the property.

What is electrical headroom?

Electrical headroom is the amount of additional power available before reaching the configured electrical limit.

Is dynamic load balancing the same as smart charging?

No. Smart charging generally controls when charging happens. Dynamic load balancing responds to actual electrical demand and adjusts how much power the EV can use.

Does every smart EV charger have dynamic load balancing?

Not necessarily. Smart charging functionality and whole-site dynamic load balancing are different features.

Does dynamic load balancing protect the main fuse?

It can form part of a strategy for keeping demand within a configured electrical limit, but the installation still needs to be properly designed.

Is the main fuse rating the same as the load-balancing limit?

Not necessarily. The configured site limit may be lower and can depend on the electrical design.

What is a CT clamp?

A CT is a current-measuring device commonly used to monitor electrical flow and provide load information to the charger.

Where should the CT clamp be installed?

It needs to be positioned so that the load-balancing system can measure the electrical demand relevant to the boundary being protected. The correct location is installation-specific.

Does solar affect EV load balancing?

Yes. Solar generation can reduce grid import and therefore change the available charging headroom.

Does a home battery affect EV load balancing?

Yes. Battery charging increases grid demand, while battery discharging can reduce it.

Can a battery create more EV charging headroom?

Potentially, by discharging and reducing grid import. Whether that is a sensible energy strategy is a separate question.

Can load balancing avoid a fuse upgrade?

Potentially, where the problem is caused by EV charging overlapping with other flexible loads. It does not guarantee an upgrade will never be required.

Can load balancing avoid three phase?

Potentially. If the issue is occasional simultaneous demand, dynamic control may allow the existing single-phase connection to be used more effectively.

Can a 7 kW charger reduce its power?

Many dynamically controlled chargers can reduce charging current, subject to the vehicle, charger and installation design.

Can an EV charger reduce all the way to zero?

Charging can be paused, but active AC charging normally has a practical minimum usable current.

What is the minimum EV charging current?

Around 6 A per phase is a useful typical reference for Mode 3 AC charging, although exact vehicle and charger behaviour varies.

Can load balancing pause the EV automatically?

Depending on the charger, yes. Charging may pause when insufficient headroom remains and resume when capacity returns.

Does dynamic load balancing work without internet?

That depends on the system. Robust electrical headroom control may operate locally even where other smart functions use cloud services.

What happens if the CT clamp fails?

Behaviour varies between products. A good system should have a defined fallback such as pausing or limiting charging.

How does load balancing work on three phase?

The system may need to consider the electrical demand and available headroom on each individual phase.

Can two EV chargers share one site limit?

Yes, with suitable compatible charging and control equipment.

Is sharing between two EVs the same as whole-home load balancing?

No. One controls how EV power is shared between vehicles; the other also considers the capacity available to the property.

Is solar charging the same as load balancing?

No. Solar charging tries to use surplus generation. Load balancing primarily protects an electrical limit.

Can smart devices interfere with each other?

Potentially. EV chargers, batteries and other independently controlled systems can respond to the same changing headroom in different ways.

Do I need a HEMS instead?

Not necessarily. Charger-level dynamic load balancing may be enough for a simple home. A HEMS becomes more useful when several flexible electrical technologies need coordinated control.

Use the Electrical Capacity the Home Actually Has

The objective is not to reserve maximum charging power for the EV all day.

It is to let the charger use spare electrical capacity when it exists and reduce demand when the house needs that capacity elsewhere.